The present invention relates generally to capacitors and more particularly to laminated capacitors with plural-layered configurations comprising at least one dielectric ceramic layer sandwiched between electrode layers.
A typical construction of a laminated ceramic capacitor is shown in U.S. Pat. No. 5,014,158 to Nishimura et al.
In U.S. Pat. No. 5,576,926 to Monsorno there is taught a capacitor with an electrically isolated electrode buried between ceramic layers.
End caps are disclosed typically in U.S. Pat. No. 4,458,294 to Womack.
It is an object of the present invention to provide a capacitor that retains superior high frequency attributes of the capacitor taught in the ""926 Monsorno Patent while reducing space needed on a mother board. Capacitors according to the present invention have more than four times the capacity of those taught in the ""926 Patent for the same size unit with the same dielectric thickness.
Another object of the present invention is further to increase resonance frequency of capacitors having buried electrodes over resonance frequencies of prior art capacitors with plural-layered configurations.
Another object of the present invention is to optimize board space utilization of capacitors.
Another object of the present invention is to provide a capacitor which can be manufactured in quantity at a low unit cost with superior quality.
Another object of the present invention is to provide a capacitor which performs well over a broad range of operating temperatures.
Another object of the present invention is to provide a capacitor which is highly reliable.
Yet another object of the present invention is to provide a capacitor that is particularly effective at very high frequencies.
In accordance with the present invention there is provided a capacitor which includes a dielectric layer having a first surface and a second surface. A first electrode is provided on the first surface. A second electrode, arranged on the second surface, is formed as a pad. The first electrode develops capacitance relative to the second electrode. The first electrode is organized to be operable at a different level of polarity from that of the second electrode.
The crux of the present invention is to position the first electrode in the ceramic and to form the second electrode on the pad. Connection to the first electrode is either from an end cap or by way of a conductive via through the dielectric layer.
The foregoing and other objects and advantages of the present invention will appear in detail hereinafter. In accordance with the present invention there is provided a laminated capacitor comprising dielectric ceramic layers sandwiched about a first electrode. A second electrically conductive layer is positioned outwardly of one of the ceramic layers and is formed as a pad.